Trees make people with depression feel more secure

"It's a planting that has quite organic and quite natural form. And the idea behind that is rather than geometry and straight lines - you don't want people to feel forced through the garden, they need to feel compelled to move into it and meander round it at their own pace, and feel at complete ease when they move through the garden.” --Matt Keightley, garden designer of RHS Feel Good Garden

available at https://www.telegraph.co.uk/news/2018/05/22/wild-untidy-gardens-better-mental-health-designer-claims-chelsea/